Surface-mount type antennas and mobile communication terminals using the same

ABSTRACT

A surface-mount type antenna and a communication terminal using the same. A radiator electrode is provided on a first principal face of a substrate. A ground electrode is provided on the second principal face of the substrate. A first feeder electrode has at least a portion thereof provided on a side face and on the second principal face of the substrate. A second feeder electrode is provided on an inner wall face of a hole formed parallel to the first and second principal faces. The first feeder electrode and the ground electrode are kept in a non-contact state. The first feeder electrode and the second feeder electrode are in electrical contact. A mobile communication terminal using the surface-mount type antenna is small in size, exhibits small variations in characteristics, and provides high productivity and reliability.

FIELD OF THE INVENTION

[0001] The present invention relates to a surface-mount type antenna foruse in a global positioning system, more particularly to a surface-mounttype antenna mounted on a portable remote terminal, and to a mobilecommunication terminal using the same.

BACKGROUND OF THE INVENTION

[0002] A system having a global positioning system mounted on a portableremote terminal for transmitting information of the present position ofthe terminal to a specific party on the other end of the connection isbeing put to practical use. For example, when a carrier of the portableremote terminal meets an emergency (such as a traffic accident), theperson can transmit information of his or her present position to aspecific place (such as a rescue center) so as to take a necessarymeasure without delay.

[0003] As antennas used on such a portable remote terminal,surface-mount type antennas have frequently been used because of theterminal being limited in size. For example, a surface-mount typeantenna disclosed in Japanese Patent Non-examined Publication No.H7-221537 has a configuration of a radiator electrode provided by athrough hole formed parallel to a principal face of a dielectricsubstrate and of a through hole formed in the direction of the thicknessof the dielectric substrate for electrically connecting a radiatorelectrode with a feeder electrode. In an art disclosed in JapanesePatent Non-examined Publication No. H7-235825, a radiator electrode anda coplanar type feeder line are provided on each of the principal facesof a dielectric substrate and they are connected by a through hole.

[0004] In both of the antennas described above, since high precision isrequired of the size of the through hole and, further, the inputimpedance of the antenna is directly affected by a connection made atthe through hole, great variations in characteristics were producedbetween products.

[0005] In the case of a surface-mount type antenna disclosed in JapanesePatent Non-examined Publication No. H9-214226, it is attempted tominiaturize the antenna by embedding the feeder electrode in thesubstrate. However, productivity was poor because such a process as tocement substrates together was required and, sometimes, great variationsin characteristics were produced. In addition, because of difference ofthermal expansion coefficient between the substrate and the feederelectrode, cracks were produced, or stress was accumulated, in thesubstrate, and, sometimes, variations in characteristics were produced.

[0006] Further, an antenna disclosed in Japanese Patent Non-examinedPublication No. H11-112221 is designed to achieve miniaturization bysuch a layout that a feeder electrode is surrounded by a radiatorelectrode. In this case, a minute distance was preset between the feederelectrode and the radiator electrode early in the designing stage toprovide the antenna with required impedance matching.

[0007] Accordingly, this type of antenna lacks adjustment means andhence variations in characteristics between products sometimes becameconsiderably great, depending on the manner of fabrication.

[0008] Further, in a surface-mount type antenna disclosed in JapanesePatent Non-examined Publication No. H11-74721, it is arranged such thatthe radiator electrode and the ground electrode are provided on the sameprincipal face, whereas no particular design is made to decreaseoccupied areas by the two electrodes. Accordingly, the dielectricsubstrate becomes large in size and, therefore, miniaturization of theantenna has been difficult to achieve.

[0009] There has been such a technical problem with these prior artsurface-mount type antennas that miniaturization of the product,decreased variations in characteristics between products, and increasedproductivity and enhanced reliability on the product cannot be attainedat the same time.

SUMMARY OF THE INVENTION

[0010] In view of the problem described above, it is an object of thepresent invention to provide a surface-mount type antenna being small insize, producing small variations in characteristics between products,and being excellent in productivity and reliability, and, in addition,to provide a communication terminal using the same.

[0011] A surface-mount type antenna to be mounted on a printed circuitboard of the present invention comprises: a substrate; a radiatorelectrode provided on a first principal face of the substrate; a groundelectrode provided on its second principal face; a first feederelectrode having at least a portion thereof provided on the secondprincipal face and on a side face of the substrate; and a second feederelectrode provided on an inner wall face of a hole formed in the sideface, or, more particularly, formed on the first feeder electrode andlocated between the radiator electrode and the ground electrode.

[0012] Further, the first feeder electrode and the ground electrode arekept in a non-contact state and the first feeder electrode and thesecond feeder electrode are in electrical contact.

[0013] Instead of providing the second feeder electrode within a hole,it is possible to use, as the second feeder electrode, a feederelectrode provided on a stepped face of a stepped portion formed bycutting step-wise a portion of the side face on the side of the secondprincipal face and close to the first feeder electrode. In this case, itmay also be practiced to provide additionally a second ground electrodeon a stepped face of a stepped portion formed by cutting step-wise aportion on the side of the second principal face of each of four sidefaces of the substrate and have this electrode electrically connectedwith the ground electrode provided on the second principal face.

[0014] As another type of second feeder electrode, a feeder electrodeprovided on an inner wall face of a groove formed in the secondprincipal face can be used and, thereby, ease of fabrication can beobtained. As a further type of second feeder electrode, such a feederelectrode can also be used that is provided on an inner wall of a grooveformed at a portion of the side face, on which the first feederelectrode is provided, parallel to the first and second principal faces.

[0015] By virtue of the above described structure, the surface-mounttype antennas according to the present invention and communicationterminals using the antenna can achieve miniaturization, reduction ofvariations in characteristics between products, and increase inproductivity of and reliability on the products.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016]FIG. 1 is a perspective view of a surface-mount type antennaaccording to exemplary embodiment 1 of the invention.

[0017]FIG. 2 is a top appearance view of the surface-mount type antennaaccording to exemplary embodiment 1 of the invention.

[0018]FIG. 3 is a plan view of the surface-mount type antenna accordingto exemplary embodiment 1 of the invention.

[0019]FIG. 4 is a side view of the surface-mount type antenna accordingto exemplary embodiment 1 of the invention.

[0020]FIG. 5 is a diagram showing input impedance and VSWR frequencycharacteristics of the surface-mount type antenna according to exemplaryembodiment 1 of the invention.

[0021]FIG. 6 is a diagram showing a directivity characteristic of thesurface-mount type antenna according to exemplary embodiment 1 of theinvention.

[0022]FIG. 7 is a perspective view of a surface-mount type antennaaccording to exemplary embodiment 2 of the invention.

[0023]FIG. 8 is a perspective view of a surface-mount type antennaaccording to exemplary embodiment 3 of the invention.

[0024]FIG. 9 is a perspective view of a surface-mount type antennaaccording to exemplary embodiment 4 of the invention.

[0025]FIG. 10 is a perspective view of a surface-mount type antennaaccording to exemplary embodiment 5 of the invention.

[0026]FIG. 11 is a perspective view showing a mobile communicationterminal according to exemplary embodiment 6 of the invention.

[0027]FIG. 12 is a block diagram showing the mobile communicationterminal according to exemplary embodiment 6 of the invention.

[0028]FIG. 13 is a perspective view showing a mobile communicationterminal according to another preferred embodiment of exemplaryembodiment 6 of the invention.

[0029]FIG. 14 is a perspective view showing a mobile communicationterminal according to a further preferred embodiment of exemplaryembodiment 6 of the invention.

[0030]FIG. 15 is a drawing showing an outline of a system using themobile communication terminal according to exemplary embodiment 6 of theinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] Each of exemplary embodiments of the present invention will bedescribed below with reference to their respective drawings.

[0032] <<Exemplary Embodiment 1>>

[0033]FIGS. 1, 2, 3, and 4 are a perspective view, a top appearanceview, a plan view, and a side view, respectively, of a surface-mounttype antenna according to exemplary embodiment 1 of the presentinvention.

[0034] Main components of the present exemplary embodiment and electriccharacteristics thereof will be enumerated below:

[0035] 1. Substrate

[0036] (a) ε_(r)

[0037] In FIGS. 1, 2, 3, and 4, substrate 1 is made of a dielectricmaterial whose relative dielectric constant ε_(r) is preferably notsmaller than 4 and not greater than 150 (more preferably, not smallerthan 18 and not greater than 130). When relative dielectric constantε_(r) is smaller than 4, the size of substrate 1 becomes too large andminiaturization of the antenna becomes unattainable. When relativedielectric constant β_(r) is greater than 150, the operating frequencyrange of the antenna becomes too narrow. Then, the operating frequencydeviates from a predetermined frequency range if there is produced asmall difference in chemical composition or a small chip on thesubstrate. Hence, such a disadvantage arises that not only desiredcharacteristics cannot be obtained but also variations incharacteristics become great. Within a range of relative dielectricconstant ε_(r) between 4 and 12, a resin substrate having a dielectricloss tangent of 0.005 or below and showing a small decrease in Q-factoris preferably used, and, within a range between 6 and 150, a ceramicsubstrate having, likewise, a dielectric tangent of 0.005 or below andshowing a small decrease in Q-factor is preferably used.

[0038] (b) Material

[0039] As concrete examples of component materials of substrate 1,glass-impregnated fluororesin, glass-impregnated thermosettingpoly-phenylene-oxide (PPO) resin, bismaleimide-triazine (BT) resin,powdered-ceramics impregnated poly-tetra-fluoro-ethylene (PTFE)laminated substrate, resin group substrate of ceramic/whisker or thelike, and ceramic substrate of forsterite group, alumina group,magnesium titanate group, calcium titanate group, zirconia-tin-titangroup, barium titanate group, and lead-calcium-titan group are used.Especially when weather resistance, mechanical strength, and economy ofthe substrate are taken into consideration, it is preferred that ceramicbe used. In this case, in order to improve flexural strength and thelike, the sintering density is preferred to be 92% or above (morepreferably, 95% or above). When the sintering density is below 92%, suchdisadvantages as decrease in the Q-factor and relative dielectricconstant ε_(r) arise.

[0040] (c) Shape

[0041] Substrate 1 may be formed in a square plate shape, a polygonalplate shape (having a triangular, rectangular, pentagonal, or such across-section), and a circular plate shape. When it is formed in apolygonal plate shape, it is preferred to be formed in a regularpolygonal shape for ease of mounting and excellent characteristicsobtainable.

[0042] Surface roughness of substrate 1 is preferred to be 50 μm orbelow (more preferably, 10 μm or below and still more preferably 5 μm orbelow). When the surface roughness is larger than 50 μm, the conductorloss of the electrode is increased and the absolute antenna gain islowered and, further, fluctuation of the effective relative dielectricconstant occurs. This, sometimes, produces a drift of the antennaoperating frequency and lowers the antenna gain in a specified frequencyrange.

[0043] In the present embodiment, the thickness of substrate 1 has beenmade uniform (the thickness at the center portion has been madevirtually equal to the thickness at the end portion) to ensure uniformcharacteristic or stabilized characteristic. However, depending on theoperating conditions or the kind of terminals on which the antenna ismounted, the thickness of substrate 1 in a specific range may be madedifferent from that in other portions. For example, a plurality ofrecessed portions or stepped portions may be provided in substrate 1 orthe thickness of substrate 1 at one end may be made different from thatat the other end.

[0044] Further by providing chamfering and tapering at corner portionsof substrate 1 as shown in FIG. 1, antenna characteristics are preventedfrom changing due to a large chip produced at corner portion 1 c ofsubstrate 1.

[0045] From the viewpoint of productivity, provision of C chamfering orR chamfering is preferable because it ensures reliable processing at thecorner portion. At this time, by making corner processing by Cchamfering or R chamfering 0.1 mm or larger (preferably, 0.2 mm orlarger), chipping off of the corner portion of substrate 1 hardly occurswhen substrate 1 is subjected to a certain shock. Even if it issubjected to a large shock, only a small chip may be produced. Thus, thetransmitting and receiving characteristics can be prevented from beingaffected. While such a chamfering or tapering process is required to becarried out regardless of the material of the substrate, it isparticularly effective when a ceramic material liable to produce a chipis used.

[0046] Incidentally, instead of carrying out such corner processing asdescribed above, an organic resin or the like may be provided at thecorner portion to prevent production of a large chip at the cornerportion.

[0047] By taking such a measure to prevent production of a chip asdescribed above, it is made possible to suppress occurrence of a failurein the fabrication process accompanied by deterioration in the antennacharacteristics on account of a produced chip. Hence, productivity andyield of antennas can be improved.

[0048] (d) Size

[0049] When breadth of an antenna denoted by L₁ (cm), length by L₂ (cm),and thickness by L₃ (cm) satisfy the following conditions, the operatingfrequency of the antenna is optimized and the external size thereof isminimized and, hence, antennas can be supplied stably and the gain andbandwidth can be secured properly:

2λ₀/(7ε_(r) ^(1/2))≦L ₁≦2λ₀/(2ε_(r) ^(1/2)),

2λ₀/(7ε_(r) _(1/2))≦L ₂≦2λ₀/(2ε_(r) ^(1/2)),

λ₀/(30ε_(r) ^(1/2))≦L ₃≦λ₀/(2ε_(r) ^(1/2)),

[0050] where λ₀ represents the free space wavelength (unit: cm) at theoperating frequency of the antenna and ε_(r) represents the relativedielectric constant of the antenna material. When the thickness L₃ islowered beyond the above mentioned range, the mechanical strength of theantenna itself is lowered and a crack or the like tends to occur. At thesame time, a drop of the antenna gain and decrease of the bandwidth iscaused and, hence, it becomes impossible for the antenna to makestabilized transmission and reception of radio waves. When it isincreased beyond the above range, the antenna size becomes too largeand, hence, it becomes impossible to make the antenna smaller andthinner.

[0051] 2. Radiator Electrode and Ground Electrode

[0052] Radiator electrode 2 and ground electrode 3 are provided on firstprincipal face 1 a and second principal face 1 b of substrate 1,respectively, as shown in FIGS. 1, 2, 3, and 4. Ground electrode 3 isprovided with terminal portions 3 a-3 e which are respectively disposedon side faces 1 c and 1 d opposite to each other. Terminal portions 3 aand 3 b are disposed on side face 1 c and terminal portions 3 c-3 e aredisposed on side face 1 d.

[0053] Although five terminal portions 3 a-3 e are provided in thepresent exemplary embodiment, the number of the terminal portions, whichmay be one or more than one, can be suitably changed depending ondesigning specifications of the antenna. Further, terminal portions maybe disposed on other side faces than side faces 1 c and 1 d.

[0054] If anything, provision of a plurality of terminal portions 3 a-3e on each of side faces 1 c and 1 d opposing each other as shown in FIG.1 improves the mounting strength and the like.

[0055] Feeder electrodes 4 a and 4 c are formed exposed to the outside,extended from side face 1 c to principal face 1 b, and held in anon-contact state with ground electrode 3. More specifically, as shownin FIG. 1, recessed portion 3 f is provided at a portion of groundelectrode 3, feeder electrode 4 c is disposed within recessed portion 3f with a gap left around the same, and feeder electrode 4 a is providedalso on side face 1 c.

[0056] Further, there is provided hole 5 in side face 1 c as shown inFIG. 1. Within this hole 5, there is provided feeder electrode 4 b withan electrode material applied to its inner wall surface. Accordingly,the feeder electrode has a configuration in which three electrodes 4 a,4 b, and 4 c are electrically connected with each other.

[0057] Especially, feeder electrode 4 a functions, mainly, as anexternal feeder portion. Since feeder electrode 4 b is disposed within aspace formed between the radiator electrode surface and the groundelectrode surface, its own inductance and the static capacitance betweenthe same and other electrodes can be varied in accordance with itslength. Thus, the same has a function of adjusting the input impedanceof the antenna.

[0058] By having hole 5 not filled up with an electrode material butleft vacant, even if there is a difference of thermal expansioncoefficient between feeder electrode 4 b and substrate 1, the thermalstress is absorbed by the hollowed portion. Hence, production of a crackin substrate 1 or accumulation of stress in substrate 1 and feederelectrode 4 b to deteriorate the antenna characteristics can beprevented. This structure is advantageous because a portable remoteterminal with the surface-mount type antenna of the present exemplaryembodiment mounted thereon can be used in an environment wheretemperature difference is extreme.

[0059] 3. Feeder Electrode

[0060] (a) Depth of Hole

[0061] With reference to FIG. 3, depth D₁ of hole 5 forming feederelectrode 4 b is preferred to be determined to satisfy expression:K=D₁/G₁>0.08, where G₁ represents the length of substrate 1. When K=1,hole 5 becomes a through hole. If K is below 0.08, the length of feederelectrode 4 b becomes too small and, hence, the static capacitancebetween feeder electrode 4 b and the radiator electrode and between thesame and the ground electrode become small, and, hence, a desiredcharacteristic becomes unobtainable. Therefore, preferable range of K isgiven by 0.08<K≦1. More preferable range is 0.1<K≦0.5, in which rangesufficiently good antenna characteristics can be obtained.

[0062] (b) Position of Hole

[0063] Although it is preferred that the center of hole 5 be positionedon center line P of breadth G2 of substrate 1 as shown in FIG. 3, adeterioration in the characteristics is not caused even if it deviatesG2/10 or so from centerline P to both sides.

[0064] It is preferred that hole 5 be shifted from center line P1 towardground electrode 3 in the direction of thickness of substrate 1. By sucharrangement of hole 5, the distance between feeder electrode 4 b andradiator electrode 2 can be made larger than the distance between feederelectrode 4 b and ground electrode 3 and, thereby, the adjustment of theantenna characteristic becomes easier to improve productivity.

[0065] (c) Diameter of Hole

[0066] Size of hole 5, denoted by t, in the direction of the thicknessof substrate 1 is preferred to be set within a range of 0.1-0.55 whenthe substrate thickness G3 is given by 1. When it is 0.1 or below,formation of feeder electrode 4 b becomes difficult and, when it is 0.55or above, the mechanical strength of substrate 1 is lowered and,further, since feeder electrode 4 b comes closer to radiator electrode2, the adjustment of the antenna characteristic becomes difficult tolower productivity.

[0067] (d) Shape of Hole

[0068] Cross-section of hole 5 is preferred to be a circular,elliptical, or rectangular shape most part thereof being not parallel toground electrode 3 and radiator electrode 2. In the case of hole 5having a rectangular shape whose longer side is parallel and opposite toground electrode 3 and radiator electrode 2, the adjustment of theantenna characteristic becomes difficult to deteriorate productivity.

[0069] A rectangular sectional shape is not entirely bad. In the casewhere the shorter side, as referred to above, of the rectangularsectional shape is parallel and opposite to ground electrode 3 andradiator electrode 2, the adjustment of the antenna characteristic canbe made easily and no problem arises.

[0070] As described above, by forming feeder electrode 4 b on hole 5 andby interconnecting the same and feeder electrodes 4 a and 4 c to providea feeder electrode assembly, an inductance is produced for each offeeder electrodes 4 a, 4 b, and 4 c and a static capacitance is providedbetween ground electrode 3 and each of feeder electrodes 4 a, 4 b, and 4c, as well as between radiator electrode 2 and each of feeder electrodes4 a, 4 b, and 4 c. Thereby, the input impedance matching for the antennais made sufficiently well.

[0071] 4. Electrode Material

[0072] As materials of radiator electrode 2, ground electrode 3, andfeeder electrodes 4 a, 4 b, and 4 c, simple metallic substance such asAg, Au, Cu, and Pd, alloy of them, or alloy of such metallic materialand other metal (such as Ti, Ni, and the like) are used. Of thesematerials, Ag, or an alloy of Ag and another metallic material, ispreferably used because of excellence of the characteristic providedthereby and of workability when forming the electrode.

[0073] Each electrode may be formed by a single layer or multiplelayers. More specifically, a metallic protection layer of Au, Pt, or Tihaving a good corrosion resistive property may be formed on the surfaceof each electrode for enhancement of corrosion proof or rust-preventingproperty.

[0074] Further, for the same purpose, the electrode surface may bechemically treated to form a protection film of epoxy group or silicongroup resin thereon. Further, each electrode may be mixed with at leastone of such elements as oxygen, nitrogen, and carbon of an amount notaffecting the characteristic, as an impurity substance.

[0075] Further, a film of another metallic material may be formed as abuffer layer between substrate 1 and each electrode to obtain improvedbonding strength and the like.

[0076] 5. Method for Fabricating Electrode

[0077] In forming electrodes, such methods as printing, plating, andsputtering are used. When it is especially desired to provide arelatively thin film thickness of the electrode, sputtering method andplating method are preferable, whereas when it is desired to provide arelatively thick film thickness, printing method is preferable. In thecase of the present exemplary embodiment, printing method providing goodproductivity is used. A paste having metallic powders of Ag, glassfrits, and a solvent mixed therein is applied to the surface ofsubstrate 1 so as to form a predetermined pattern and then the productis subjected to a heat treatment and, thereby, each electrode isproduced.

[0078] It is preferred that the film thickness of each electrode be0.01-50 μm (more preferably, 1-40 μm). When the film thickness of anelectrode is smaller than 0.01 μm, it sometimes occurs that the filmthickness becomes thinner than the skin depth and the antenna gain isthereby lowered.

[0079] When the film thickness of an electrode becomes 50 μm or larger,falling off of the electrode tends to occur and, in addition, adisadvantage of increased material cost arises due to increases in theamount of coating.

[0080] 6. Antenna Characteristics

[0081]FIG. 5 is a chart showing input impedance and VSWR frequencycharacteristics of a surface-mount type antenna in exemplary embodiment1 of the present invention. As shown in FIG. 5, the antenna of thepresent embodiment has point B lying along center line B1 of the Smithchart and located at the middle point. Generally, the input impedance ofan rf circuit is frequently matched with 50 Ω. In this case, it is knownfrom FIG. 5 that the input impedance is matched with 50 Ω.

[0082] Directivity characteristic of the surface-mount type antenna ofembodiment 1 of the invention is shown in FIG. 6. It is known that theantenna has a good characteristic over a range from the direction of thezenith (angle of elevation: 90°) to the direction of the horizon (angleof elevation: 0°).

[0083] In the present exemplary embodiment, feeder electrode 4 b hasbeen provided by forming the electrode all over the inner wall face ofhole 5, while not filling up the interior of hole 5 with the electrodematerial. However, the electrode may be formed on a portion of the innerwall. By virtue of this arrangement, all of substrates 1 may befabricated so as to have hole 5 of the same depth and, thereafter, thelength of feeder electrode 4 b formed in hole 5 may be adjustedaccording to the specifications of the antenna. Thus, it becomesunnecessary to change the length of the hole itself case by case and,hence, component sharing can be made. As one concrete example, after adielectric or insulating material is filled to a predetermined lengthfrom the bottom portion of hole 5 of a constant depth, a feederelectrode may be formed on the inner wall surface. Thus, the length offeeder electrode 4 b can be adjusted easily.

[0084] As described above, a surface-mount type antenna small in size,producing small variations in characteristics, and excellent inproductivity and reliability can be realized by the present exemplaryembodiment.

[0085] <<Exemplary Embodiment 2>>

[0086]FIG. 7 shows a perspective view of a surface-mount type antennaaccording to exemplary embodiment 2 of the present invention.

[0087] There is provided step portion 6 extended from side face 1 c toprincipal face 1 b of substrate 1 by cutting a portion off side face 1 cand principal face 1 b as shown in FIG. 7 to form feeder electrode 4 aon one step face 4 a′ of step portion 6 (hereinafter, “step face” meanseach of two faces along the principal face and along the side face atthe stepped portion). By virtue of this structure, a signal fed intofeeder electrode 4 a produces electromagnetic coupling between the edgeportion of feeder electrode 4 a and radiator electrode 2, whereby afunction as an antenna is obtained. At this time, since feeder electrode4 a is placed inwardly from the outside shape of substrate 1 because ofthe provision of step portion 6, it can have a more suitable and stableelectrode arrangement in feeding signals into radiator electrode 2.Thus, stabilized antenna characteristics can be obtained.

[0088] Further, when the antenna of the present exemplary embodiment ismounted on a printed board, a higher strength against bending stress onthe substrate can be obtained because the soldered portion of the feederelectrode is placed inwardly from the circumference of substrate 1.

[0089] <<Exemplary Embodiment 3>>

[0090]FIG. 8 shows a perspective view of a surface-mount type antenna ofexemplary embodiment 3 of the present invention.

[0091] Step portions 6 a, 6 b, 6 c, 6 d, and 6 e equivalent to stepportion 6 (FIG. 7) formed in exemplary embodiment 2 are providedextended from side faces 1 c and 1 d to principal face 1 b as shown inFIG. 8. Then, fixed electrodes 3 a, 3 b, 3 c, 3 d, and 3 e are providedon step faces 3 a′, 3 b′, 3 c′, 3 d′, and 3 e′ of step portions 6 a, 6b, 6 c, 6 d, and 6 e.

[0092] In the surface-mount type antenna structured as described above,since soldered portions of the electrodes are recessed further inwardlyfrom the circumference of substrate 1 than in embodiment 2, a higherstrength can be obtained against bending or flexure of the substratewhen the antenna is mounted on a printed board, whereby reliability onthe antenna can be enhanced. Further, the size of the land patternformed on a printed board on which the antenna of the present embodimentis mounted can be placed within the outside size of the antenna, adecrease in space of the printed board can be achieved.

[0093] <<Exemplary Embodiment 4>>

[0094]FIG. 9 shows a perspective view of a surface-mount type antennaaccording to exemplary embodiment 4 of the present invention. In thepresent embodiment, groove 7 as shown in FIG. 9 is provided in principalface 1 b instead of hole 5 shown in FIG. 1. Feeder electrode 4 b isformed on the inner wall surface of groove 7 and the same iselectrically connected with feeder electrode 4 a formed on side face 1 cof substrate 1 as shown in FIG. 9.

[0095] Formation of such groove 7 is easier than formation of a hole inthe fabricating process and such an advantage can be obtained thatprovision of an electrode on the inner wall surface is also easier.

[0096] <<Exemplary Embodiment 5>>

[0097]FIG. 10 shows a perspective view of a surface-mount type antennaaccording to exemplary embodiment 5 of the present invention. Slit 8 isformed in side face 1 c of substrate 1 parallelly to the direction ofthe width or length of substrate 1, perpendicularly to the direction ofthe thickness of the same, and on the side closer to the groundelectrode. Feeder electrodes 4 c and 4 a formed on principal face 1 band side face 1 c, respectively, are electrically connected with feederelectrode 4 d in slit 8 formed on a portion of one of the two inner sidefaces, which is closer to principal face 1 b. (Note that feederelectrode 4 d is not on the bottom face of the slit 8.)

[0098] The surface-mount type antenna structured as described aboveallows a signal to be passed through feeder electrode 4 c and 4 a andelectromagnetic coupling to be produced between the open end of feederelectrode 4 d and radiator electrode 2 and, thus, it functions as anantenna. The surface-mount type antenna has no need to embed the feederelectrode in the substrate 1. Further, since slit 8 can be produced moreeasily than hole 5 in exemplary embodiment 1, such advantages can beobtained that the adjustment of the antenna characteristic becomeseasier and productivity is enhanced.

[0099] <<Exemplary Embodiment 6>>

[0100] Exemplary embodiment 6 is an example of use of the surface-mounttype antenna of each embodiment for a mobile remote terminal.

[0101] In a mobile remote terminal of the present embodiment shown inFIG. 11 and FIG. 12, a signal is received by transmit-receive antenna105 at the time of call in. Thereupon, controller 111 allows thereceived information to be displayed on display unit 104 and sets theterminal at a call-in mode to establish a communication. Then,transmission and reception of voice and data are performed.

[0102] On the other hand, at the time of call out, the party on theother end of the connection is selected by operating unit 103,controller 111 allows transmitter 106 to generate a transmission signaland radiate it out into space, and, at the same time, sets the terminalat a call-out mode. Then, upon receiving a signal from the party on theother end, establishes a communication and performs transmission andreception of voice and data.

[0103] Further, at the time of making an emergency call, an emergencysignal is generated from emergency input unit 108 and, then, controller111 allows transmitter 106 to generate a transmission signal to beradiated out into space through antenna 105.

[0104] After a communication is established, a transmitted signal fromGPS is received by planar antenna 110 and information of the presentposition obtained by detection in position detector 109 is radiated fromantenna 105. Although, in this case, one piece of antenna 105 is used inthe drawing, such cases are also possible in which diversity antennas,antennas for a dual or triple type mobile communication terminal to beapplicable for a plurality of communication systems, or a plurality ofantennas are used.

[0105] Further, in cases where a dual or triple type mobilecommunication terminal is used, a plurality of transmitters 106 andreceivers 107 are sometimes provided therein.

[0106] As emergency input unit 108, that allows inputting to be made bya simple operation is preferred and it may sometimes be constructed ofvarious sensors. As planar antenna 110, surface-mount type antennadescribed in embodiment 1-5 is used.

[0107] While a general outline of the present embodiment was describedabove, each unit of the present embodiment will be described below indetail.

[0108] 1. Operating Unit 103

[0109] Operating unit may for example be constituted of a combination ofa plurality of buttons as shown in FIG. 11 or it may be such that has arotatable or revolvable member, not shown, provided in case 112 andallows, by rotation or revolution of such a member, characters and menusto be sequentially displayed for selection on display unit 104.Otherwise, voice-operated entry or handprint entry may be used.

[0110] 2. Display Unit 104

[0111] As display unit 104, an LED, an organic electroluminescent (EL)display, or that having a plurality of LEDs mounted thereon may be used.Further, monochrome display, color display, or partly color display maybe used.

[0112] 3. Emergency Input Unit 108

[0113] As emergency input unit 108, such a device, not shown, may beused, which, by having a button or the like not normally in use providedon case 112, allows an emergency signal to be generated from emergencyinput unit 108 by a push on the button or, by having various sensorssuch as a temperature sensor and a shock sensor disposed on the insideor outside of case 112, allows a sensor to generate a detected signal inemergency. When a shock sensor is used, for example, case 111 may becollided against the ground in emergency. Then, the shock sensor detectsa shock at this time to generate a detected signal and, in responsethereto, emergency input unit 108 generates an emergency signal.

[0114] Further, it is also possible to allow an emergency signal to begenerated by having a special button on operating unit 103 depressed fora long time or by having a specific key word entered. In such case,provision of emergency input unit 108 becomes unnecessary. Thus, byproviding operating unit 103 with the function of emergency input unit108, this emergency input unit 108 can be eliminated to simplify theapparatus.

[0115] 4. Planar Antenna 110

[0116] Planar antenna 110 is preferred to be disposed at the rear ofspeaker 102 as shown in FIG. 11 so that the principal face of antenna110 directly confronts speaker 102. On the back side of such units asoperating unit 103, except for speaker 102, there are disposed othercircuit boards. Therefore, if antenna 110 is disposed there, mobilecommunication terminal 121 itself becomes thick or a portion of case 112comes to bulge at this position. Then, not only appearance is impairedbut also antenna 110 is shielded to lower the receiving sensitivity.Furthermore, since the antenna is shielded by hand while the terminal isoperated, undesired deterioration of the receiving sensitivity iscaused.

[0117] Further, terminal 121 can be made thinner by juxtaposing planarantenna 110 and speaker 12 as shown in FIG. 13.

[0118] Although the terminal becomes somewhat thicker, by arranging thetop face of case 112 and the principal face of antenna 110 to confronteach other as shown in FIG. 14 or by arranging the antenna to be tilteda predetermined angle so that the surface of the radiator electrode ofantenna 110 is turned toward the zenith during the time ofcommunication, the receiving sensitivity can be enhanced.

[0119] Since planar antennas 110 are the surface-mount type antennas ofthe present invention providing high productivity, the mobilecommunication terminals of the present exemplary embodiment alsoprovides enhanced productivity. Especially, micro-strip antennasemploying a substrate having an excellent high-frequency characteristic,such as a substrate of fluorocarbon resin and of dielectric ceramic,relative dielectric constant ε_(r) of which is within a range of 4-150,are preferably used for micro-strip antennas 110. That using adielectric ceramic substrate of which ε_(r) is within a range of 20-150,in particular, can constitute an antenna being small in size but havinga high receiving sensitivity and, hence, the same is very much suitedfor miniaturization of the terminal.

[0120] When arrangement of planar antenna 110 is consideredquantitatively, it is preferred that P<0.35×L be satisfied, where L andP represent the sizes of mobile communication terminal and planarantenna 110, respectively, measured from top face 112 a of the case asshown in FIG. 11. More preferable condition is P<0.3×L, and still morepreferable condition is P<0.25×L. The same rule applies to the caseshown in FIG. 13.

[0121] As described above, by having planar antenna 110 incorporated inmobile communication terminal 121, a mobile communication terminal beingsmall in size, having good receiving sensitivity, and providing highproductivity and reliability can be realized virtually without the needfor changing other components and layout of members.

[0122] 5. Operation

[0123] (a) At the Time of Call in

[0124] When there is a call in, a call-in signal is sent from receiver107 to controller 111. Controller 111, in response to the call-insignal, allows display 104 to display predetermined characters and thelike.

[0125] When a button for accepting the call in is depressed in operatingunit 103, controller 111 receives the signal from the operating unit andset each unit at a call-in mode.

[0126] Thereafter, a signal received by antenna 105 is converted into avoice signal in receiver 107 and the voice signal is delivered as avoice from speaker 102. A voice fed in from microphone 101 is convertedinto a voice signal and radiated out into space through transmitter 106and antenna 105.

[0127] (b) At the Time of Call out

[0128] When making a call out, a signal to make a call out is sent fromoperating unit 103 to controller 111. Then, a signal denoting thetelephone number of the party on the other end of the connection is sentfrom operating unit 103 to controller 111. Upon receipt of the signal,controller 111 allows transmitter 106 to generate a transmission signalincluding the telephone number so as to be radiated out into space fromantenna 105.

[0129] When the party on the other end has received the signal and acommunication has been established, antenna 105 receives an acknowledgesignal transmitted from the party on the other end. Receiver 107 detectsthe acknowledge information and sends it to controller 111. Thereupon,controller 111 sets each unit at a call-out mode.

[0130] Thereafter, a signal received by antenna 105 is converted into avoice signal in receiver 107 and the voice signal is delivered fromspeaker 102 as voice. Voice fed in from microphone 101 is converted intoa voice signal and radiated out into space through transmitter 106 andantenna 155.

[0131] (c) At the Time of Emergency Call

[0132]FIG. 15 shows a communication system for use in emergency. Anexample of operation at the time of emergency call will be describedwith reference to FIG. 12 and FIG. 15.

[0133] When a transmitted signal A (FIG. 15) from at least three GPSsatellites 120 is received by planar antenna 110 (FIG. 12), positiondetector 109 (FIG. 12) measures the position of mobile communicationterminal 121 (FIGS. 11-14). At this time, position measurement by planarantenna 110 and position detector 109 is carried out, for example, atall times, intermittently (at regular intervals), or upon an inputtingoperation made in operating unit 103.

[0134] When power saving in mobile communication terminal 121 itself isnot needed to be considered, it is desired that the measurement becarried out at all times. This provides an advantage that accurateposition information can be obtained.

[0135] When, on the other hand, power saving is to be considered, themeasurement is carried out at regular intervals and hence an advantageis obtained that consumed power in terminal 121 can be reduced.

[0136] In the event of an emergency, information of occurrence of theemergency is fed in from emergency input unit 108 or operating unit 103.When the signal is transmitted to controller 111, controller 111 callsup the telephone number of specific office 122 (such as the police, afire department, and a first-aid center) stored in its own memory oranother memory unit and radiates the transmission signal out into spacethrough transmitter 106 and antenna 105. When it is detected bycontroller 111 that a communication is established with the party on theother end of the connection of the line through antenna 105 and receiver107, controller 111 obtains the position information (the latitude andlongitude) detected by position detector 109 at present or a short timebefore.

[0137] Then, the position information is transmitted to office 122through transmitter 106 and antenna 105. At this time, predeterminedmessages (such as name, address, and chronic disease) may also betransmitted.

[0138] Mobile communication terminal 121 is in receipt of positioninformation from transmitted signal A from GPS 120. Terminal 121operates in emergency as described above and it first transmits signal Bto base station 123. Then, base station 123 directly transmits signal Cto office 122, whereby a communication is established between terminal121 and office 122. Sometimes, base station 123 establishes acommunication between terminal 121 and office 122 through a publicswitched telephone network.

[0139] Further, signal D is transmitted from terminal 121 tocommunication satellite 124 and communication satellite 124, in turn,sends signal E directly to office 122, whereby a communication isestablished between terminal 121 and office 122. Though it is not shown,signal D from communication satellite 124 may sometimes be sent to itsearth station and the earth station establishes a communication betweenterminal 121 and office 122 through a public switched telephone network.

[0140] When mobile communication terminal 121 is capable ofcommunicating with both base station 123 and communication satellite124, controller 111 may control transmitter 106 so that a signal at afrequency for base station 123 is first transmitted therefrom. When aspecific signal cannot be received within a predetermined period oftime, controller 111 may judge that it is impossible to make aconversation with base station 123 and may, then, switch thecommunication over to that using communication satellite 124.

[0141] A concrete example of operation of mobile communication terminal121 in emergency will be described below. Assume that a vehicle withmobile communication terminal 121 mounted thereon had a traffic accidentin a suburb and, as a result, the driver is seriously injured that hecannot speak. If the seriously injured person operates emergency inputunit 108, the above described operations are performed in terminal 121and such information as the present position is transmitted to office122.

[0142] In response to the position information, office 122 urgentlysends an emergency ambulance to the spot of accident and performs suchwork as rescue of the injured person. However, in order not tomistakenly send an ambulance to the spot when emergency input unit 108is erroneously operated at ordinary times, it may be arranged such thatoffice 122, upon receipt of an emergency communication, sends back avoice or signal to the spot and dispatch an ambulance car only when therequest for rescue is confirmed or when no answer is obtained. Thus,bidirectional confirmation of the fact can be made and a reliable systemfree from error can be structured.

[0143] While an example in which voice is transmitted and received hasbeen described in the present embodiment, the same effect can beobtained when character data is transmitted and/or received.

[0144] As described in the foregoing, the present invention realizes asurface-mount type antenna small in size, showing only small variationsin characteristics between products, and providing high productivity andreliability, as well as a communication terminal using the same.

What is claimed is:
 1. A surface-mount type antenna comprising: (a) asubstrate; (b) a radiator electrode provided on a first principal faceof said substrate; (c) a ground electrode provided on a second principalface of said substrate; (d) a first feeder electrode having at least aportion thereof provided on the second principal face and on a side faceof said substrate; and (e) a second feeder electrode provided on aninner wall face of a hole formed in the side face, wherein said firstfeeder electrode and said ground electrode are kept in a non-contactstate and said first feeder electrode and said second feeder electrodeare in electrical contact.
 2. The surface-mount type antenna accordingto claim 1, having another ground electrode than said ground electrodeat a portion of the side face of said substrate, wherein said groundelectrode and said another ground electrode are kept in electricalcontact.
 3. The surface-mount type antenna according to claim 1, whereinthe hole is formed on said first feeder electrode.
 4. The surface-mounttype antenna according to claim 1, wherein the hole is a non-throughhole.
 5. The surface-mount type antenna according to claim 1, whereinthe hole is a through hole.
 6. The surface-mount type antenna accordingto claim 1, wherein the hole is formed parallel to the first principalface and the second principal face.
 7. The surface-mount type antennaaccording to claim 1, wherein the hole has a cross-sectional shape beingconstant along its depth.
 8. The surface-mount type antenna according toclaim 1, wherein the hole has a cross-sectional shape varying along itsdepth.
 9. The surface-mount type antenna according to claim 1, whereincross-sectional shape, inclusive of circular shape, elliptical shape,and rectangular shape, of the hole has smaller parallel portion, thannonparallel portion, to said radiator electrode and ground electrode.10. The surface-mount type antenna according to claim 1, wherein thehole in the side face is positioned closer to said ground electrode thanto said radiator electrode.
 11. The surface-mount type antenna accordingto claim 1, wherein relationship between a depth of the hole, denoted byD₁, and a length of the substrate in the direction of the depth, denotedby G₁, is expressed as 0.1≦D₁/G₁≦0.5.
 12. The surface-mount type antennaaccording to claim 1, wherein a size of the cross-section of said holein the direction of thickness of said substrate is within a range of10-55% of the thickness of said substrate.
 13. The surface-mount typeantenna according to claim 1, wherein said substrate is formed of asingle substrate.
 14. A surface-mount type antenna comprising: (a) asubstrate; (b) a radiator electrode provided on a first principal faceof said substrate; (c) a ground electrode provided on a second principalface of said substrate; (d) a first feeder electrode having at least aportion thereof provided on the second principal face of said substrate;and (e) a second feeder electrode provided on a stepped face of astepped portion formed by cutting step-wise a portion of a side face ofsaid substrate on the side of the second principal face, wherein saidfirst feeder electrode and said ground electrode are kept in anon-contact state and said first feeder electrode and said second feederelectrode are in electrical contact.
 15. The surface-mount type antennaaccording to claim 14, having another ground electrode than said groundelectrode provided at a portion of the side face of said substrate,wherein said ground electrode and said another ground electrode are inelectrical contact.
 16. The surface-mount type antenna according toclaim 14, further comprising (f) a second ground electrode provided on astepped face of a stepped portion formed by cutting step-wise a portionof each of four side faces of said substrate on the side of the secondprincipal face, wherein said first ground electrode and said secondground electrode are in electrical contact.
 17. The surface-mount typeantenna according to claim 16, having another ground electrode than saidground electrode at a portion of the side face of said substrate,wherein said ground electrode and said another ground electrode are inelectrical contact.
 18. A surface-mount type antenna mounted on aprinted circuit board comprising: (a) a substrate; (b) a radiatorelectrode provided on a first principal face of said substrate; (c) aground electrode provided on a second principal face of said substrate;(d) a first feeder electrode having at least a portion thereof providedon the second principal face and on a side face of said substrate; and(e) a second feeder electrode provided on an inner wall face of a grooveformed in the second principal face, wherein said first feeder electrodeand said ground electrode are kept in a non-contact state and said firstfeeder electrode and said second feeder electrode are in electricalcontact.
 19. The surface-mount type antenna according to claim 18,wherein the groove is formed on said first feeder electrode on saidsecond principal face.
 20. The surface-mount type antenna according toclaim 18, having another ground electrode than said ground electrodeprovided at a portion of the side face of said substrate, wherein saidground electrode and said another ground electrode are in electricalcontact.
 21. A surface-mount type antenna comprising: (a) a substrate;(b) a radiator electrode provided on a first principal face of saidsubstrate; (c) a ground electrode provided on a second principal face ofsaid substrate; (d) a first feeder electrode having at least a portionthereof provided on the second principal face and on a side face of saidsubstrate; and (e) a second feeder electrode provided on an inner wallface of a groove formed in the side face, wherein said first feederelectrode and said ground electrode are kept in a non-contact state andsaid first feeder electrode and said second feeder electrode are inelectrical contact.
 22. The surface-mount type antenna according toclaim 21, having another ground electrode than said ground electrodeprovided at a portion of the side face of said substrate, wherein saidground electrode and said another ground electrode are in electricalcontact.
 23. A mobile communication terminal dealing with a first signalincluding at least one of data signal and voice signal and a secondsignal including position information comprising: (a) a first antennareceiving and transmitting the first signal; (b) a converter unitperforming at least one of generation of the first signal from at leastone of the data signal and the voice signal, and generation of at leastone of the data signal and the voice signal from the first signal; (c) asecond antenna for receiving the second signal; (d) a position detectorfor detecting the position information from the second signal; (e) anemergency input unit for an operator of said mobile communicationterminal to make an entry in emergency; (f) a storage unit for storinginformation of a party on the other end of the connection of said mobilecommunication terminal; (g) a display unit for displaying information tobe read by the operator; (h) a controller for controlling operation ofsaid mobile communication terminal; and (i) a case of said mobilecommunication terminal, wherein said second antenna is a surface-mounttype antenna comprising: (j) a substrate; (k) a radiator electrodeprovided on a first principal face of said substrate; (l) a groundelectrode provided on a second principal face of said substrate, (m) afirst feeder electrode having at least a portion thereof provided on thesecond principal face and on a side face of said substrate; and (n) asecond feeder electrode provided on an inner wall face of a hole formedin the side face, wherein said first feeder electrode and said groundelectrode are kept in a non-contact state and said first feederelectrode and said second feeder electrode are in electrical contact,and wherein said controller, when the operator has made a predeterminedentry into said emergency input unit: allows information of the party onthe other end of the connection to communicate therewith in emergency tobe retrieved from said storage unit; allows said converting unit togenerate a first rf signal from information of the party on the otherend of the connection to communicate therewith in emergency so as to betransmitted from said first antenna; allows a communication to beestablished after said first antenna has received a response signal fromthe party on the other end of the connection; and allows said convertingunit to convert the position information obtained by said positiondetector unit into the first signal so as to be transmitted from saidfirst antenna.
 24. The mobile communication terminal according to claim23, wherein said second antenna is positioned within a range of 0.35×Lfrom the top face of said case, where L denotes the size of said mobilecommunication terminal along its length.
 25. The mobile communicationterminal according to claim 23, wherein said mobile communicationterminal includes a speaker contained in an upper portion of said case,and said second antenna is contained in said case such that the secondprincipal face of said second antenna confronts the back side of saidspeaker.
 26. The mobile communication terminal according to claim 23,wherein said mobile communication terminal includes a speaker and saidspeaker is juxtaposed with said second antenna.
 27. The mobilecommunication terminal according to claim 23, wherein said secondantenna is contained in said case such that the top face of said case isarranged to be parallel and opposite to the first principal face of saidsecond antenna.
 28. The mobile communication terminal according to claim23, wherein said second antenna is contained in said case such that thetop face of said case is arranged to be opposite to the first principalface of said second antenna with an angle therebetween.